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Allison V-3420

The V-3420 is a 24-cylinder double-vee, twin-crankshaft, liquid-cooled engine derived from the V-1710, a 12-cylinder engine that powered such World War II aircraft as the Lockheed P-38, Bell P-39 and the Curtiss P-40.

Essentially, the V-3420 is two V-1710 engines mounted on a single crankcase with the two crankshafts geared together. It powered several experimental U.S. Army Air Forces aircraft including the XB-19A, XP-58, XB-39, XP-75 and the P-75A. None of these aircraft were produced in quantity, and only about 150 V-3420s were built.

The V-3420 on display shows the configuration used in a P-75A. Mounted behind the cockpit in the P-75A, the engine was connected by dual driveshafts that ran under the cockpit to a gearbox that drove two coaxial contra-rotating propellers.

Type: 24-cylinder, liquid-cooled, double-vee with gear-driven supercharger and exhaust-driven turbo-supercharger
Displacement: 3,420 cu. in.
Weight: 2,655 lbs.
Maximum rpm: 3,000
Maximum hp: 2,885

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